1. Field of the Invention
The present invention relates to a reverse rotation preventive device for an engine of a motorcycle, and particularly to a reverse rotation preventive device for an engine of a motorcycle which is compatible with various operating conditions and is highly convenient to use.
2. Description of Background Art
It is known that when the rotating speed of a crankshaft is insufficient for starting an engine through cranking by use of a kick starter, a phenomenon of “reverse rotation” may occur in which the crankshaft is rotated in the reverse direction due to an explosion force attendant on ignition and the kick pedal is thereby pushed back.
Japanese Patent No. 3945645 discloses a reverse rotation preventive device for an engine in which, when the rotating speed of a crankshaft after its start of rotation is lowered to or below a predetermined value, the ignition at an ignition device is inhibited and the ignition inhibited condition is maintained until a new cranking operation is conducted.
Meanwhile, during the operation of a motorcycle, there is a situation in which even upon momentary locking of the rear wheel due to a braking operation during operation, the braking operation is immediately canceled to thereby continue the operation. In relation to such a situation, in the case of the reverse rotation preventive device for an engine described in Japanese Patent No. 3945645, when the rotating speed of the crankshaft is lowered to or below a predetermined value attendant on the locking of the rear wheel, a reverse rotation preventive function operates to inhibit ignition. Then, even if the brake is released in this condition and the rear wheel is rotated by the inertia of the vehicle body to thereby rotate the crankshaft, it may be impossible to restart the engine because the ignition inhibited condition is maintained. Therefore, when the engine is stopped due to the operation of the reverse rotation preventive function during operation, it is necessary to once stop the vehicle for the purpose of carrying out a new cranking operation.
In addition, particularly in a batteryless vehicle, the application of a system in which a reverse rotation preventive function is canceled by turning off the power supply for an ECU has the following problem. When the rotation of the crankshaft is recovered by releasing the brake immediately after the operation of the reverse rotation preventive function attendant on the locking of the rear wheel, the supply of electric power by a generator is restarted before the ECU voltage is lowered below a predetermined reset voltage. This may results in that the reverse rotation preventive function is not canceled. Thus, the engine cannot be restarted.